What is OSPF (open Short Path First)?
It uses a link state routing algorithm and falls into the group of interior routing protocols, operating within a single autonomous system (AS).
What are six [6] features of OSPF
- Classless - supports VLSM & CIDR.
- Efficient – triggered updates (not periodic), uses SPF.
- Fast convergence
- Scalable
- Secure - supports encrypted updates when config’d
- AD = 110
What are three [3] components of OSPF?
- Data Structure
- Routing packets
- Dijkstra’s SPF alogorithm
What are four [4] data structures of the OSPF
- Creates & maintains three DBs:
- Adjacency DB -> neighbor table
- Link-state DB (LSDB) -> topology table
- Forwarding DB -> routing table
What is a Single-Area OSPF?
smaller networks; usually area 0
What is a Multiarea OSPF?
Multi-Area – 2-layer hierarchy – larger networks
All areas must connect to area 0
What is ABR (Area Border Routers)?
Interconnect routers are Area Border routers
What are Hello Packets Intervals?
Every 10 sec (default multiaccess & P2P)
Every 30 sec (default NBMA) (non-broadcast multiple access)
What is a Dead interval?
period router waits before declaring neighbor down
Hello packets are transmitted to what IPV4 address?
224.0.0.5
Hello packets are transmitted to what IPV6 address?
FF02::5
FF02::6
What happens after a dead interval occurs?
default is 4 Hello interval
floods LSDB about dead neighbor out all OSPF interfaces
What are the five [5] OSPF Packet Types
- Hello
- DBD (Database Description)
- LSR (Link-State Request)
- LSU (Link-State Update)
- LSAck (Link-State Acknowledgement)
What is the 7 state of OSPF?
- Down
- Initiate
- 2-Way
- Ex-Start
- Exchange
- Loading
- Full
What is the Password Recovery process?
Do a hard Reset (Switch on and Off)
Ctrl + Break
Type confreg 0x2142
What are the three [3] orders of Router ID
- 32 bit dotted decimal
- highest loopback IP address
- highest active IP address
